I would like to know if the parameter SM_PROXYREQUEST is sent by CA SiteMinder Web Agent by default. If it's the case, do you know a way to deactivate it?

Answer:

The SM_PROXYREQUEST HTTP Header is set to store the URL requested initially by the user when the Web Agent is acting as Reverse Proxy. This header is set by the Web Agent at the front end, so by using this header, the backend server can get information about the original URL which was requested by the end user. This is controlled by the following ACO parameter:

ProxyAgent Specifies if a Web Agent is acting as a reverse proxy agent.

When the value of this parameter is yes, the CA Single Sign-On Web Agent on the front-end server preserves the original URL that the user requested in the SM_PROXYREQUEST HTTP header. This header is created whenever protected and unprotected resources are requested. The back-end server can read this header to obtain information about the original URL. Default: No

The header will be set only when ProxyAgent ACO parameter is set to YES in the ACO. So this header will not be displayed when ProxyAgent is set to NO in the ACO of front end server.